After a random NASCAR explosion that looked like something you’d see during an NHRA drag race, the driver himself said he’d “never experienced anything like that” in 35 years of racing. It seems as if the sanctioning body itself doesn’t know what happened, either.

Before we get to the details, here’s a video of the incident:

The explosion with 23 laps to go ended the day for Xfinity Series driver Derrike Cope in the Zippo 200 at Watkins Glen International, but Motorsport reports that the driver was not injured. Cope pulled off from the competition surface before something exploded under the hood, taking the straightaway shortcut rather than what NASCAR calls the “bus stop” turn.

There was speculation about what could have happened on Twitter—including comments from Rodney Childers, crew chief for print Cup Series driver Kevin Harvick, and Mike Kelley, car chief for Sprint Cup driver Ricky Stenhouse Jr.—but Motorsport reports that NASCAR ultimately decided to impound the car and take it back to the research and development center to figure out the mystery.

Time for the guessing game, it seems—what do you think happened?

Update, Aug. 7 at 4:05 p.m. ET: If you guessed tire failure, congratulations. It wasn’t an ordinary tire failure, though—it was about as weird as they get.